Ibuprofen (I) is a well-known nonsteroidal antiinflammatory drug which possesses analgesic and antipyretic activity. ##STR1##
Ibuprofen has been marketed as a racemic mixture of the S(+) and R(-) enantiomers; however, recently there have been suggestions in the literature regarding an increased pharmaceutical benefit for S(+)-ibuprofen relative to the racemic mixture, see, for example, A. Sunshine et al U.S. Pat. No. 4,851,444, D. Lowe et al EPO publication 267,321, K. Williams et al Brit.J. of Pharm. 35 3404 (1986).
Ibuprofen as a carboxylic acid can form salts with bases, such as basic amino acids, examples of which are lysine and arginine. The low solubility of the acid form of ibuprofen is overcome by the use of the lysinate salt of ibuprofen. U.S. Pat. No. 4,279,926 describes the use of the lysine salt of Ibuprofen in relieving pain and inflammatory conditions in warm-blooded animals. However, there is no description in the literature of the compound S(+)-ibuprofen-L-lysine, i.e. the L-lysinate salt of S(+)-ibuprofen, or other L-amino acid salts of S(+)-ibuprofen; there is also no description of S(+)-ibuprofen-D-lysine or other D-amino acid salts of S(+)-ibuprofen.